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Since search is limited 4L80E to NP205 options.

Discussion in 'The Garage' started by Leadfoot, Mar 4, 2004.

  1. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    I tried doing a search as I remember a few members here had done it and I believe Wes and/or others had some pics and options. I know there were two versions of the 32 spline 205 long input and short input as well as round adapter (short) and figure 8 (tall) adapter. I'm assuming the round adapter would be better as I have broken several tall adapters at the feet (TH350/700R4-NP205). Does this make sense. Also is the short adaptered case the long or short input and would I/should I swap it out for the other????? Also what is needed. I think someone here did the round pattern 205 to 4L80 with a round adapter machined to fit each (seems the easier of the adapters to make/buy). I am definitely going the 4L80 to 205 route and need to find the 205 so I need to know which one I should be looking for. Swapping out the input shaft is easy as I would be rebuilding it anyways, but I need to find the correct case and adapter.

    Also what shifter mods were done to make it work?


    Thanks.

    Leadfoot
     
  2. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    I think the easiest way to do it would be to use a '85+ 205 from a TH400 truck. The adapter will work but you have to do some grinding (I believe to clear the tranny pan) and an o-ring step will need to be machined onto it. Once done the adapter should work on the 4L80E so assuming you have the correct tailshaft (I'm guessing there's more than one like most trannys) the rest should bolt up with the OE t-case shifter.

    FYI - U2Slow posted the adapter modifications either here r on Pirate once.
     
  3. thatK30guy

    thatK30guy 1 ton status Premium Member

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    John pretty much nailed it. I've got a thread saved to my "favorites" and while they are long, they are very informative. Pay good attention to which adaptor is to be used and their part numbers so if you need to search for one, you will have the number on hand. /forums/images/graemlins/waytogo.gif

    Adapting the 4L80E to the 205.
     
  4. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Wes, thanks for the link /forums/images/graemlins/thumb.gif
    Some of the pictures don't come up, is it me or because they moved....?

    Nvrenuf:
    Which route did you go?
    You said something about grinding for the post 85 and up adapter, how much grinding and where (adapter)? Also what is the front driveshaft clearance with this setup? I know on my 700r4 to 205 I had to modify the pan as the driveshaft was hitting it (using AA's shortened output shaft in the tranny).

    I don't want to do this and find out there was a better way. If driveshaft clearance isn't an issue than I will most like go that route (short adapter). Also for cutting the tranny output shaft (as is described when going this route), how much is cut off and using what (I don't want to weaken it by cutting it incorrectly).

    Thanks.
     
  5. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    Really, the only info I have is what I posted as I haven't actually done the mod. I do have short 400/205 adapter at home, I can compare it to my crew cab (factory 4L80E/205 - adapter discontinued by GM) and see if there are any length differences. As for driveshaft clearance, assuming the 400/205 adapter is the same length as the one in my truck theres plenty of room.
     

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